Evidence for a unidimensional 15-item version of the CASP-19 using a Rasch model approach

Abstract

Aim

The aim of this study is to explore the dimensionality of the CASP-19—a quality-of-life measure for early old age—and to assess the stability of the item locations over time and changes in person measures.

Methods

The Rasch partial credit model was applied to the CASP-19 data obtained from Waves 1 and 3 (N = 9,407 and N = 7,732) of the English Longitudinal Study of Ageing to assess item fit, dimensionality and differential item functioning (DIF).

Results

Five items demonstrated category disordering for the last two response categories of the CASP-19 (which were collapsed), and 4 items demonstrated item misfit and were removed from the analysis. Cronbach’s alpha indicated good internal consistency for both waves (0.87 for Wave 1 and 0.88 for Wave 3). There was no evidence of multidimensionality, and no significant DIF was observed for gender. When the two datasets were combined, no statistically significant differences were observed between the two sets of item locations. A statistically significant difference was found for the mean person measure [t(5,524) = 17.88, p < 0.001)], suggesting quality of life improves as people age.

Conclusion

A 15-item unidimensional factor structure was observed for the CASP-19, which was stable over time.

Hyde, M., Wiggins, R. D., Higgs, P., & Blane, D. B. (2003). A measure of quality of life in early old age: The theory, development and properties of a needs satisfaction model (CASP-19).
Aging & Mental Health,7(3), 186–194.
CrossRef

3.

Howel, D. (2012) Interpreting and evaluating the CASP-19 quality of life measure in older people.
Age Ageing,41(5), 612–617.

4.

Grant, R., & Bowling, A. (2011). Challenges in comparing the quality of life of older people between ethnic groups, and the implications for national well-being indicators: a secondary analysis of two cross-sectional surveys.
Health and Quality of Life Outcomes,5(9), 109.
CrossRef

5.

Wiggins, R. D., Netuveli, R. D., Hyde, G. M., Higgs, P., & Blane, P. (2008). The evaluation of a self-enumerated scale of quality of life (CASP-19) in the context of research on ageing: A combination of exploratory and confirmatory approaches.
Social Indicators Research,89(1), 61–77.
CrossRef

6.

Sim, J., Bartlam, B., & Bernard, M. (2011). The CASP-19 as a measure of quality of life in old age: evaluation of its use in a retirement community.
Quality of Life Research,20(7), 997–1004.
PubMedCrossRef

Evidence for a unidimensional 15-item version of the CASP-19 using a Rasch model approach

Auteurs:

Yemi Oluboyede Adam B. Smith

Publicatiedatum

01-11-2013

DOI

https://doi.org/10.1007/s11136-013-0367-z

Uitgeverij

Springer Netherlands

Tijdschrift

Quality of Life Research
An International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation - An Official Journal of the International Society of Quality of Life Research
Uitgave 9/2013
Print ISSN: 0962-9343
Elektronisch ISSN: 1573-2649